An electric power switch device is a main circuit switchgear disposed between a generator and a main transformer in a power plant and the like. A live part, which is a main body of the electric power switch device, is insulated and supported by an insulating support disposed on a mounting surface in the atmosphere.
The insulating support needs to be able to withstand a weight of the live part and an operation load associated with a switching operation, and thus requires a certain mechanical strength.
In addition, a fold may be provided in the insulating support. An object of the fold is to ensure a dielectric strength by lengthening a creeping distance in advance to lengthen a leakage length since insulation performance is degraded when a surface of the insulating support is stained.
Further, in a general configuration, metal inserts are provided on both end surfaces of the insulating support to fix the insulating support to each of the live part and the mounting surface.
Furthermore, Patent Literature 1 discloses a configuration in which metal fittings are buries in both end surfaces of a pillar-shaped portion made of resin included in a resin insulator, and a fold for ensuring a surface dielectric strength is provided on an external surface of the pillar-shaped portion.